INTRODUCTION

Irritable bowel syndrome (IBS) is a functional intestinal disorder, characterized by changes of the bowel function, associated with abdominal pain, without any structural cause, and has a negative impact on quality of life ¹. Nowadays, the Rome IV criteria are the gold standard for the diagnosis of IBS, they are based on the abdominal pain, which can go from a mild symptom with no repercussions to a severe one that interferes with daily activities. This pain must be related to changes in intestinal habit, such as alternation of the stools between diarrhea and constipation. Generally, the pain tends to ease after defecation ². These symptoms occur chronically, at least once a week in the last 3 months, with a duration of at least 6 months ^3,4; may be accompanied by abdominal distension and increased flatulence, and do not usually occur at night, nor do they tend to wake up the patient, nor do they generate a negative impact on weight or alterations in laboratory tests ⁵. There are subtypes of IBS according to the predominant pattern of stools, based on the Bristol scale, which classifies stool according to its shape and consistency into seven types ⁶. In IBS where constipation predominates (IBS-C), there are hard stools (Bristol type 1 and 2), dischezia and sensation of incomplete evacuation; on the other hand, in case diarrhea predominates (IBS-D), there are soft stools not very voluminous (Bristol type 6 and 7) ^6,7.

Gastrointestinal (GI) disorders are highly prevalent; approximately in more than 40% of the population worldwide ^8,9; between 10 to 21% of adults and adolescents have symptoms consistent with IBS, with a predominance in the female sex ¹⁰. Various studies have been developed looking for the prevalence of IBS using the Rome IV criteria. In 2021, Alvizuri et al. did a cross-sectional study of 130 people from an Andean community between 18 and 93 years old and found a prevalence of 13.1% ¹⁰. In that same year, Pontet et al. did a review of 16 studies published in Pubmed and Lilacs, carried out in nine Latin America countries and found an average prevalence of IBS of 6.98% ¹¹. In 2020, Oka et al. did a systematic review of studies published in MEDLINE, where they found that the IBS prevalence according to Rome IV criteria was 3.8% ¹² in adults. The Rome 2020 Foundation conducted virtual and in-person surveys of adults from 33 countries worldwide, finding a prevalence of 4.1% and 1.5%, respectively.

Various studies have been made to identify the factors associated with this disorder. Choghakhori et al. evaluated the differences in IBS symptoms according to sex, for which they included 90 people, using the Rome IV criteria, where they reported that the female sex not only presents a higher frequency of this pathology, but also had more severe symptoms; furthermore, they observed that proinflammatory cytokines such as IL-17 and TNFalpha had slightly higher values in females ¹³. The study mentioned above by Alvizuri et al., also explored associated factors such as age, sex, a higher educational level, the consumption of harmful substances, among others, and found that being female, a higher educational level, and a younger age had a statistically significant association, however this was not the case for the consumption of harmful substances ¹⁰. Akhondi et al. conducted a crosssectional study in adults and evaluated body max index (BMI) and abdominal circumference, and found that IBS was more prevalent in people with abdominal obesity (BMI greater than or equal to 30 in both sexes, and abdominal circumference greater than or equal to 102 cm in men and 88 cm in women), but no significant association was found between IBS and overweight or abdominal obesity ¹⁴. Lee et al., conducted a meta-analysis with a total of 27 studies with the objective of comparing the levels of depression and anxiety between patients with IBS and healthy controls, they included 2293 patients with IBS and 4951 healthy controls, and used scales to measure depression and anxiety, it was concluded that the levels of these pathologies were higher in those who suffered from IBS ¹⁵.

On the other hand, the COVID-19 pandemic could have increased GI diseases, because it is known that SARSCoV-2 compromises the GI system, producing "postinfection-functional GI disorder (PI-FGID)" ¹⁶. It is known that SARS-CoV-2 not only produces respiratory symptoms, but by binding to ACE2 receptors ¹⁷, it also affects the GI tract, where these receptors function as regulators of the intestinal microbiota and the innate response, so this virus can cause GI symptoms such as abdominal pain, diarrhea, nausea and vomiting ¹⁸. This is why there are cases in which GI symptoms precede respiratory symptoms or cases in which COVID-19 infection manifests only with GI symptoms. This was evaluated by Tian et al. in a review study that included studies collected by the World Health Organization (WHO) published in PubMed, carried out in patients with a confirmed diagnosis of COVID-19, where they found that diarrhea was the most common symptom (2%-49.5%) and abdominal pain, the least reported (2.2%6%).

Finally, there are few studies on the prevalence of IBS in medical students using the Rome IV criteria. Vargas et al., carried out an observational, retrospective, descriptive cross-sectional study in medical students from a university in Lima, in which they found a prevalence of IBS of 12.4% using the Rome III criteria ²⁰. However, the Rome IV criteria, allow to encompass the population better, since they take into consideration a longer duration of the presence of symptoms. Furthermore, as observed in the study published by Black CJ et al., where all the demographic and symptomatological data of the patients were collected prospectively in the first clinical visit, they concluded that the Rome IV criteria had a better diagnostic criteria than Rome III criteria, since they demonstrated a likelihood ratio of 4.82 for the Rome IV criteria compared to 2.45 for the Rome III criteria, in addition to presenting a higher specificity (82.9%) and sensitivity (82.2%) ²¹.

The objective was to determine the prevalence of IBS in medical students, through the use of a validated instrument using digital tools, and to explore the associated factors with the increase in IBS symptoms such as age, sex, anxiety, depression, overweight, obesity, alcohol consumption, tobacco, drugs and COVID-19 infection (to explore which factors, such as age, sex, anxiety, depression, overweight, obesity, alcohol consumption, tobacco, drugs and COVID infection, are associated with the increase in IBS symptoms).

MATERIALS AND METHODS

Descriptive observational cross-sectional study with exploration of associations, with non-probabilistic sampling, until reaching the total sample by subgroups, with the target population being those people of legal age, from 5th to 7th year from the medical career at the "Universidad Peruana Cayetano Heredia" (UPCH) from Lima, Peru, in 2023. These students were contacted through their promotion delegates, to whom the link of the questionnaire was shared, which they could access through their institutional email (Figure 1). The inclusion criteria were students of both sexes and of legal age, who gave their consent to participate and who did not have previously diagnosed GI disease. The exclusion criteria were considered the risk factors such as personal or family history of GI cancer, presence of GI bleeding, positive Thevenon test, night pain, unexplained spontaneous weight loss, and presence of palpable abdominal mass.

Figure 1 Flow diagram of study. 

To calculate the sample size of this study, the OpenEpi version 3 program was used; 511 students were set as the population size (N) given that the 5th year had 170 students (33.27% of the total sample), the 6th year had 164 students (32.09% of the total sample), and the 7th year had 177 students (34.64% of the total sample). A value of 10% was considered as an anticipated hypothetical frequency based on the study by Alvizuri et al. ¹⁰. The design effect was 1 and a total sample size (n) of 110 students was obtained, applying a 95% interval confidence. Considering that the three classes that participated in the study each had a different number of students, the number of participants per class was calculated using a simple rule of three, obtaining a total of 37 students from 5th year, 35 students from 6th year and 38 students from 7th year.

Operational definition of variables:

These variables will be registered through a Google Forms sent virtually.

The Rome IV criteria were used as a validated instrument to classify whether or not a student met the diagnosis of IBS. These criteria consist of chronic recurrent abdominal pain associated with at least two of three criteria, which include a change in the frequency or appearance of stools, as well as pain related to defecation ^4,6. The Bristol Scale was also used, which classifies the stool according to its shape and consistency in seven types ⁶, and it also allows to classify IBS into four subtypes (Table 1).

Table 1 Demographic characteristics of total vs IBS participants. 

* The Bristol scale was evaluated in the general population and with it the IBS subtype was classified in those who had the Rome IV criteria. IBS-C: Irritable bowel disease-constipation, IBS-M: Irritable bowel disease-mixed, IBS-D: Irritable bowel disease-diarrhea.

The data collected through Google Forms, which was sent virtually, was taken as the source of information. The information obtained was entered into Google Sheets and a database was created on this site. The absolute and relative frequencies (percentages) were calculated, and the tables were made in Google Sheets. The data was analyzed with the statistical package STATA version 17. Descriptive statistics were used with proportions and means and their respective confidence intervals. To explore associations between the variables, the Chi-square test was used considering a statistical significance of p<0.05.

RESULTS

Response to the questionnaire was obtained from 195 students, 64 of them (32.82%) presented at least one exclusion criterion such as personal or family history of GI cancer (18 participants), previously diagnosed GI disease (16 participants), bleeding in stools in the last 6 months (15 participants), among other risk factors. From the participants with previously diagnosed GI disease, the most common was gastritis in 15 participants. On the other hand, 8 participants did not answer the total questionnaire, 2 participants were not part of the educational institution, and 1 participant did not give its consent to participate, they were excluded from the study. From the excluded participants, a group presented symptoms compatible with IBS according to Rome IV criteria, but organic causes would need to be ruled out. For this reason, 131 students were considered as valid samples, after accepting the informed consent and the use of their data. Of the total sample, 64 participants (48.85%) were women and 67 (51.15%) were men. Participants had an average age of 24.04 years old, being the minimum age 21 years old, and the maximum, 34 years old, and 84 students (64.12%) were below the average age. Of the total number of students, 52 (39.69%) belonged to seventh year; 41 (31.30%), to sixth year; and 38 (29.01%), to fifth year (Table 1).

According to the Rome IV criteria, 23 students (17.56%) were diagnosed with IBS. Of these, 14 (60.87%) were women and 9 (39.13%) were men. Ten students (43.48%) belonged to the 7th year; five (21.74%), to 6th year; and eight (34.78%), to 5th year (Table 1). Regarding the IBS symptoms, all participants reported suffering abdominal pain frequently. Despite not being part of the Rome IV criteria, 17 participants (73.91%) reported that the symptoms intensified when eating food and 5 (21.74%) when having rest; on the other hand, 20 students (86.96%) mentioned that this symptom was relieved with defecation. Furthermore, 21 (91.30%) presented abdominal distention (Table 2). According to the defecation habit, 10 (43.48%) students reported changes in the frequency and appearance of feces; 7 (30.43%), changes in frequency but not in appearance; 4 (17.39%), changes in appearance but not in frequency, and 18 (78.26%) had alternation between diarrhea and constipation. Likewise, when relating IBS to the Bristol scale, the most frequent subtype of IBS was constipation in 7 students (30.43%), while the least frequent one was diarrhea in 4 of them (17.39%) (Table 1).

Table 2 Clinical characteristics of total population vs population with IBS. 

Respecting the other associated factors, 13 (56.52%) students had a normal BMI, 7 (30.43%) were overweight and 3 (13.04%) had obesity. It was also found that 9 (39.13%) had a diagnosis of Major Depressive Disorder (MDD) and 7 (30.43%) had Generalized Anxiety Disorder (GAD) diagnosed by a psychiatrist, 9 (39.13%) had history of COVID-19 infection. Finally, regarding the presence of harmful habits, 11 (47.83%) consumed alcohol, and 3 (13.04%) consumed tobacco. On the other hand, of the total sample, we found that 34 students (25.95%) had a history of MDD; 36 (27.48%), GAD; and 51 (38.93%), COVID-19 infection (Table 1).

DISCUSSION

This is the first research about IBS in medical students using digital tools in Lima, Perú. Students of the last three years of study of the medical human career from UPCH were considered as population of this research, since there are no studies carried out in this population using the current Rome IV criteria, nor carried out after the pandemic, nor using online tools. In this population, there was a significant percentage of students who did not have the inclusion criteria, so they were not part of the sample studied, since some organic causes had to be ruled out, for which they were recommended to be evaluated by a medical specialist.

The prevalence of IBS obtained is higher than the one described in the general population and in medical students in Peru, also than the one found in Latin American countries and by the Rome Foundation worldwide ^9-12. Our results reflect that approximately 1 in 5 students in the last years of study of the medical career at UPCH present IBS according to Rome IV criteria. This prevalence is higher than the 13.1% found by Alvizuri et al., who found a positive association between the diagnosis of IBS and the highest educational level and lowest age in years, their study was carried out mainly up to the school educational level and had a greater range of ages evaluated ¹⁰. Therefore, the prevalence found would be in line with what was described in our population; however, no statistically significant association was found between IBS and ages, or years of study (Table 1). Women consistently have more IBS, this predominance is widely known in the literature, where there are different theories such as hormonal factors, greater visceral stimulation and greater perception of pain ²⁴; in addition, the higher prevalence of mental illnesses such as anxiety and depression exists in the female gender ^10,13.

This is consistent with a study carried out by Bjorkman et al., where they analyzed data from questionnaires given to patients with an established diagnosis of IBS over an eight-year interval, where they found that female patients presented greater severity in terms of GI symptoms, greater presence of anxiety and lower quality of life, compared to the opposite sex ²⁵. However, in our study, no association was found between the presence of IBS and female sex, although the higher frequency it had (Table 1).

The most common subtype of IBS was constipation (IBS-C) (30.43%) followed by the diarrhea type (IBS-D) (17.39%) (Table 1). This data coincides with what was described by Choghakhori et al., who described that IBS-C is the most common both in the female and general population, followed by mixed subtype (IBS-M); while IBS-D was more common in men ¹³. However, in this study, it was found that the most frequent subtype in men was also IBS-C (44.44%), while the number of patients in women was equal between the IBS-C and IBS-D, both with a frequency of 21.42%. In this study, a positive association was found between having diarrhea-type stools (6 and 7 according to the Bristol scale) and IBS (Table 1).

According to a report published by the WHO in 2020, the prevalence of anxiety and depression increased by 25% worldwide, affecting more women and young people, being the stress by isolation one of the main causes ²⁶. On the other hand, it was found that the prevalence of mental illness such as generalized anxiety disorder (GAD) and major depressive disorder (MDD) is higher compared to other groups ²⁷, since 53.44% of our population studied mentioned having GAD or MDD as a history, with 25.95% of those having MDD and 27.48% of those having GAD. Gutierrez et al. made a systematic review of literature published in PubMed and MedLine, where it was found that the general prevalence of MDD was 2 to 21% ²⁸, while Vargas et al. made a cross-sectional analytical study in medical students at different universities in Peru, where it was found that the prevalence of MDD was 13.5% ²⁹; in both studies, it was more frequent in female sex. Our study reveals a higher prevalence of MDD than the previously mentioned studies. On the other hand, the prevalence of GAD is lower than the prevalence found by Szuhany et al. of 34%, but we must consider that this is in the general population ³⁰. In addition, it is important to mention, without being an object of study, that one out of two students reported having a history of MDD or GAD; of which 14.50% had both. However, no association was found between these diseases and the presence of IBS (Table 1). Finally, it must be considered that there may have been underdiagnosed cases of MDD and GAD, taking into account that it is possible that there are students who did not have a history of a diagnosis established by a psychiatrist, or other conditions included in mood disorders, such as persistent depressive disorder or dysthymia ³¹.

The literature describes an association between the psychiatric diseases mentioned and COVID-19 disease, Mejia et al. made a systematic review in Pubmed and MEDLINE, where it was found that the prevalence of MDD and GAD in health workers during the COVID-19 pandemic was 26.6% and 36.4%, respectively ³². On the other hand, Pacheco et al. made a descriptive cross-sectional study in people diagnosed with COVID-19 disease, where it was found that the prevalence of MDD and GAD was 25.22% and 34.15%, respectively ³³. Mohammadian et al., made a cross-sectional study in health workers, where they found that those with COVID-19 infection or who had contact with infected patients had a higher risk of depression and anxiety ³⁴. On the other side, despite what was established in previous studies, no association was found between IBS and COVID-19 infection. This was also the case of IBS and BMI, or IBS with the consumption of harmful substances, in which no statistical association was found. (Table 1).

It is important to raise awareness about the perception of this syndrome in the studied population, future health service providers, about the high prevalence and importance of this pathology and not consider it an unreal disease as mentioned in the study by Henick et al., who conducted surveys to 106 medical students about their knowledge and attitudes towards functional and organic pathologies (IBS and inflammatory bowel disease, respectively), being organic pathologies considered more relevant than functional pathologies ³⁵.

Regarding the limitations, when answering the questionnaire virtually, there was no availability for participants to ask additional questions or comments and there was a considerable percentage of students who met the ROME IV diagnosis criteria for IBS but could not be included because they presented at least one exclusion criteria; at the same time, the type of non-probabilistic sampling, since our study is a descriptive study, does not give the possibility of generalizing, but it does give the possibility of raising hypotheses. On the other hand, there were also strengths such as the use of digital tools to carry out the surveys, which allowed us to reach a large majority of students and be able to answer it quickly and safely on any electronic device. This study allows us to learn more about the prevalence of this little-studied syndrome in our country and, since IBS is a common pathology, this study can be the basis for future research and highlight the importance of this diagnosis and management.

In conclusion, the prevalence of IBS in students from the last three years of study of medical career was 17.56%, the highest compared to studies of the general population and in medical students using the Rome IV criteria; due to this high prevalence, it is important to do a clinical follow-up of these students. Of the associated factors studied, the clinical presentation of diarrhea, according to the Bristol scale, was the one that was associated with IBS; on the other hand, the female sex had a high frequency without association. It is important to mention that one in two (53.44%) students reported having a history of Major Depression or Generalized Anxiety disorder, and one in seven had both. Furthermore, 38.93% had a history of having a positive result on a COVID-19 test. Finally, we observed that one in three students (32.06%) suffers from chronic abdominal pain.